Saturday, February 28, 2009

I'm a little upset that Pluto still isn't being referred to as a planet. Officially, along with Eris, Haumea and Makemake (Kuiper Belt Objects), Ceres (the biggest Asteroid), and technically Charon (as Pluto-Charon is really more of a binary planetary system with 2 extra moons), Pluto is listed as a dwarf planet.

Now don't get me wrong, I totally support a better system of classification. But part of me just wants things to make sense. What is the second word in the term dwarf planet. It's fucking "planet." I'm sorry, but if you want to strip Pluto of it's planetary status, you at least have to admit that it still falls under the broad category of "planet."

I know, the whole mnemonic is thrown off, and if only to prevent the other interlopers from getting in, I'll agree that technically Pluto isn't a planet. Yes, it's sperical, yes it orbits the sun, but no, it hasn't cleared it's neighborhood of space debris. That's cool, whatever.

Just call me when the IAU decides decides to stop dicking around and integrate the planetary negro league.

2 comments
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Actually, Pluto IS a planet. The whole question depends on how one defines planet, and this is still very much up for debate. The IAU definition was adopted by only four percent of its members, most of whom are not planetary scientists. It was rejected by hundreds of professional astronomers in a petition led by Dr. Alan Stern, Principal Investigator of NASA's New Horizons mission to Pluto.

Stern and like-minded scientists favor a broad planet definition in which a planet is defined as any non-self-luminous spheroidal body orbiting a star. By that definition, Pluto is very much a planet. We can distinguish between types of planets through use of subcategories such as terrestrial planets, gas giants, ice giants, dwarf planets, etc.

The requirement that an object clear its neighborhood to be considered a planet was arbitrarily imposed by this tiny percent of the IAU and is not accepted by Stern and many other scientists as a necessary condition for planethood.

However, a logical solution would be to establish dwarf planets as a subclass of planets that are spherical but do not gravitationally dominate their orbits. That would satisfy both dynamical and geophysical criteria.